* Newton's First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
* Gravity: Gravity is the only force acting on a projectile, and it acts vertically downwards. This means gravity only affects the vertical motion of the projectile, not its horizontal motion.
* No Horizontal Force: Since there's no horizontal force to slow it down or speed it up, the projectile continues moving horizontally at a constant velocity.
Think of it this way: Imagine throwing a ball straight up. It goes up, slows down, and falls back down due to gravity. But if you throw it horizontally, the ball still falls down due to gravity, but it also continues moving forward at the same speed you threw it.
Important Note: This is a simplification. In the real world, air resistance does play a role, and it will gradually slow down the projectile's horizontal motion. However, for many situations, neglecting air resistance provides a good approximation.
